Optimisation of dosages and application methods for Agrobion granulated soil improver in combination with mineral fertilisers for grain crops on southern chornozems in Northern Kazakhstan

The study aimed to identify effective ratios of the biological product and mineral fertilisers to increase yields and soil activity. The study presented the results of a comprehensive study of the effect of the granular preparation “Agrobion” and different doses of mineral fertilisers (NP) on the agrobiological parameters of oats and spring wheat in the southern black soil of Northern Kazakhstan. The experiment covered 18 variants of fertiliser combinations, including an absolute control, a standard dose of NP, as well as different doses of Agrobion (100-300 kg/ha) and their combinations with ¼, ½, ¾ and full NP norms in the main and pre-sowing methods of application. The highest biological activity of the soil was observed in the variant with 200 kg/ha of “preparation” and ½ NP, which was accompanied by a fivefold increase in the number of nitrogen fixers, actinomycetes and cellulose-degrading bacteria compared to the control. The yield of oats in the earing phase reached 49.52 g/vessel with this combination, and the maximum field germination (72.14%) was recorded at the pre-sowing application of 100 kg/ha of Agrobion with a full dose of NP. Analysis of the chemical properties of the soil showed a decrease in electrical conductivity and maintenance of optimal pH with a moderate reduction in NP and the use of the product. The results demonstrated that the optimal doses of Agrobion (100-200 kg/ha) in combination with ½ or ¾ of the calculated NP rate provide the highest yield, microbiological activity and germination. Excessive doses (300 kg/ha) or a sharp decrease in NP led to a decrease in efficiency. A correlation was found between the dose of Agrobion, yields and soil fertility indicators. The recommended combination to increase agroecological efficiency is 200 kg/ha of “granular preparation” with ½ NP at the main application. The practical value of this study is the substantiation of the optimal doses of Agrobion and NP, which reduces the mineral load without loss of yield, which contributes to resource conservation and environmental protection of agriculture